435 research outputs found
Quantum chaos in one dimension?
In this work we investigate the inverse of the celebrated
Bohigas-Giannoni-Schmit conjecture. Using two inversion methods we compute a
one-dimensional potential whose lowest N eigenvalues obey random matrix
statistics. Our numerical results indicate that in the asymptotic limit,
N->infinity, the solution is nowhere differentiable and most probably nowhere
continuous. Thus such a counterexample does not exist.Comment: 7 pages, 10 figures, minor correction, references extende
Optimal suspension settings for ride comfort of road vehicles
In this paper a numerical study is presented for the effect of the settings of the suspension parameters of a road vehicle for the ride comfort. The chassis of the IK GMC midibus model is investigated as an example. The suspension parameters are represented by hard springs and dampers. By the appropriate choice of the suspension parameters it can be achieved that the influence of the dynamical forces is minimal for the oscillation of the carbody and for the dynamically computed internal forces, respectively. The nonlinear constrained optimization models provide appropriate tools to investigate the effect of the suspension parameters for the average acceleration and displacement of the chassis, respectively
On the behaviour of concentrically braced frames subjected to seismic loading
This paper deals with the causes and the development of weak storey mechanisms in concentrically braced frames subjected to seismic action. In order to investigate this phenomenon, different braced frames were designed in accordance with Eurocode provisions. The design parameters and the obtained structures are presented in the paper. Later the results of a comprehensive nonlinear time history analysis carried out with various accelerograms are shown emphasizing the presence of weak storeys. The connection between the behaviour of the brace and the occurrence of the weak storey is investigated. It is described how the plastic deformation of the diagonals and the development of the weak storey are related. A theoretical influence of the brace deformation on the modal response of the braced frames is introduced and also proven by means of signal processing of the displacement time series of the numerical experiments. In the last chapter a possible redesign method is introduced to rule out the occurrence of weak stories
Weighted network modules
The inclusion of link weights into the analysis of network properties allows
a deeper insight into the (often overlapping) modular structure of real-world
webs. We introduce a clustering algorithm (CPMw, Clique Percolation Method with
weights) for weighted networks based on the concept of percolating k-cliques
with high enough intensity. The algorithm allows overlaps between the modules.
First, we give detailed analytical and numerical results about the critical
point of weighted k-clique percolation on (weighted) Erdos-Renyi graphs. Then,
for a scientist collaboration web and a stock correlation graph we compute
three-link weight correlations and with the CPMw the weighted modules. After
reshuffling link weights in both networks and computing the same quantities for
the randomised control graphs as well, we show that groups of 3 or more strong
links prefer to cluster together in both original graphs.Comment: 19 pages, 7 figure
Xylan-Degrading Catalytic Flagellar Nanorods
Flagellin, the main component of flagellar filaments, is a protein possessing polymerization ability. In this work, a novel fusion construct of xylanase A from B. subtilis and Salmonella flagellin was created which is applicable to build xylan-degrading catalytic nanorods of high stability. The FliC-XynA chimera when overexpressed in a flagellin deficient Salmonella host strain was secreted into the culture medium by the flagellum-specific export machinery allowing easy purification. Filamentous assemblies displaying high surface density of catalytic sites were produced by ammonium sulfate-induced polymerization. FliC-XynA nanorods were resistant to proteolytic degradation and preserved their enzymatic activity for a long period of time. Furnishing enzymes with self-assembling ability to build catalytic nanorods offers a promising alternative approach to enzyme immobilization onto nanostructured synthetic scaffolds
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